Bail flaw detector mechanism



April 27, 1937. c.. a ROEDE' Re. 20,343

RAIL FLAW DETECTOR MECHANISM Original Filed April 27, 19:52 2 Sheets-Sheet 1 INVENTOR Charles BJZOQde B i oRNEY A ril 27,1937. B, EDE Re. 2o,343

RAIL FLAW DETECTOR MECHANISM Original Filed April 27. 1932 2 Shets-Sheet 2 I m Munm I Tb mumm f? ff INVENTOR Charles B.Roede Reis'sued Apr. 27, 1 937 PATENT OFFICE BAIL DETECTOR MECHANISM Charles B. Itoede, Ridgeileld, N. 1., assignor to Sperry Products. Inc., Brooklyn, N. Y., a corporation of New York Original No. 2,036,829. dated April 7, 1936. Serial No. 607,728,'April 27, 1932. Application for reissue February 18, 1937, Serial No. 126,527

"Claims.

paratus of the type employed on the well-known Sperry rail flaw detector cars. In these cars the detector equipment comprises a source of current within the car, which is supplied to the rail by means of brushes to send the current through the rail and establish an electromagnetic field surrounding the same. Any variations in this field caused by the presence of internal fissures are picked up during the movement of the car by means of induction coils which are maintained a constant distance above the rail surface so that normally they cut a constant number of lines of force, but on encountering the region of a flaw they will cut a different number of lines of force. The coils are connected in opposition so that variations in current supply will not have any eflect on the output of said coils, while the presence of a flaw will cause one coil to cut more lines of force than the other and hence generate a differential E. M. F.

It has been found desirable to employ more than two coils for .the reasons set forth in the patent to Harcourt C. Drake, No. 1,960,968, granted May 29th, 1934 for Flaw detector unit. The chief advantage of such an arrangement is that it avoids the condition which arises when one coil is symmetrically located with respect to the railhead. In such position a coil is apt to miss a centrally located fissure because such a fissure causes increase and diminution of flux at the sides, and the coil adds up the increase and diminution to yield the same total flux as in a sound part of the rail. In said patent there is disclosed the use of two pairs of coils in staggered relation wherebythe defect Just described is avoided because each coil coacts with only one side of the railhead and therefore does not sum up the total of increase and diminution of .flux. I have found that it is possible to obtain the same result now obtained by the use of two pairs of coils by utilizing only three coils suit-' ably connected and positioned.

It is a further object of my invention to provide a detector unit which willconsist of a plurality of sets ofdetector coils, each set comprising three coils. I

, It is a further object of my invention to provide a detector unit comprising an odd number of coils more than one in number, that is, three, five, or any greater number,

It is a further object of my invention to provide a detector unit which will comprise several sets of detector coils, each set consisting of an odd number of coils greater than one.

' springs l6, i1.

(Cl. 175-483) This invention relates to rail flaw detector ap- In the coils as heretoforeemployed, there was utilized a core substantially u-shaped, the arms of said U extending downwardly into close proximity of the rail. I have found that it is desirable that the inner arm of said U be shortened or entirely eliminated since thereby fewer false indications were caused.

Still further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawings,

Fig. l' is a side elevation of a portion of a Sperry rail flaw detector car showing the detector mechanism suspended therefrom,

Figs. 2-7, inclusive, are .plan views, largely diagrammatic, showing the various coil arrange- 'nents of the detector unit. Fig. 8 is a vertical section through a detector unit showing my improved core for the induction coil. Fig. 9 is an end elevation of the core shown in Fig. 8.

Figs. 10-14, inclusive, are wiring diagrams showing various methods of electrically connecting the coils disclosed in Figs. 2-7 inclusive.

Referring to Fig. 1, there is disclosed a detector mechanism such as is employed on the Sperry detector car. A portion of the car body it is shown having suspended therefrom the current brush carriage ll whose front and rear sets of brushes i2 and it are designed to lead current into and out of the rail R, the said current being supplied from a. source of current (not shown) within the car. riage supports in turn the searching unit or detector carriage I! by means such as bolts and Said carriage may ride along the rail on any suitable means, such as rollers l8, and supports thereon, by any suitable means, such as bolts l9 and springs 20, the searching unit II which may consist of a plurality of induction coils designed to cut the lines of force of the electromagnetic field surrounding the rail R. The said coils normally cut a uniform number of lines of force and induce a constant E. M. I"., but upon enteringtheregion of a flaw said coils cut a different number of lines of force to induce a different E. M. I". Heretofore, these coils have been, employed in pairs, the coils of each pair being opposed so that only the dif ferential E. M. F. generated by said pair of coils resulted whena flaw was encountered. Said E. M. 1". after being suitably amplified, was caused as a recorder.

The current brush car-v In the p tent to Harcourt c. Drake, No. 1,900,- 968, there is disclosed the idea of employing a plurality of pairs of detector coils, the coils of each pair being opposed. Thus, four, or any even number of coils, could be ployed either in staggered relation as shown in said application or in line. In this invention I have disclosed a method by which I can obtain by the use of three coils the same results as are obtained by said patent by the use of two pairs of coils. For this purpose I may employthe arrangement shown,

for example, in Figs. 1 and 2. In Fig. 1 the coils are shown enclosed in cylinders 25 mounted within the searchunit 2i. Saidcoils may be arranged as shown in Fig. 2. Here it will be seen that one coil 30 is displaced with respect to two other coils, ii and 32. By suitably inter-connecting said three coils I have disclosed how the same eifect is obtained as in the case of two pairs of coils in staggered relation. Thus, re-

ferring to Fig. 14, it will be seen that coils I0.

and 8! act as one pair of coils and II and 32 act as another pair. The unit as a whole is balancedso that for a variation which affects all ings so that the sum total of the output of said coils when all are caused to respond simultaneously to the same changing electromagnetic field will be sero. On entering the region of a'ilaw,

itwill be seen that coil II, for example will first.

cut a different number of lines of force so as to unbalance said unit and then each of the remaining coils ill and 32 on passing through a reglow: of fiaw will also unbalance the unit,'sc that three separate indications, each comprising a positive and negative impulse, willbe obtained.

The coils are so positioned that these impulses are additive, especially since said impulses may first be rectified as disclosed in the patent to Harcourt C. Drake, No. 1,955,953, granted April 24, 1934.

In Figs. 10-13, inclusive, I have shown still other methods of interconnecting the set of three coils so that the equivalent of two pairs of opposed coils is obtained. g In these forms, all of the coils are the same, that is, they have the same number of turns. In Fig. 10, for instance, coil Si is equal to and opposed to coil ll. Said two coils act as a pair. Similarly, coils 3| and I! are equal and opposed and act as a pair. In other words, I have in effect provided two pairs of coils but I have utilized one common coil in each pair.

In Fig. 11, a slightly'modified arrangement gives the output between coils I and SI equal and opposite to the output between coils I0 and 32. Thus, while the pair of coils ll and Il may give an impulse first positive and then negative, the

output between coils so and a would give an impulse first negative and then positive.

In Fig. 12 I have shown still another form of wiring wherein coils SI and SI form -one pair, while II and '2 form the other pair. In Fig. 13, the form of wiring shown in Fig. 12 has been modified to give the opposite phases in the same manner as in Fig. 11. :Thethree coils may be arranged as shown in Flgl2 with one coil staggered laterally across the rail with respect to the other two coils, or they may bearranged'in' line as'shown in Fig. 3-. v

A somewhat different arrangement is disclosed in Fig. 4 wherein the end coil is offset laterally with respect to the other two coils instead of the middle coil being offset as disclosed in Fig. 2.

In Fig. 5 is shown still another arrangement of the set of'coils' wherein said coils are progressivclyoifset laterally so that each coil coacts the impulses from the various coils are additive.

Also, when several sets of 'coils are employed as in Fig. 6, not only are the impulses of the coils within each set additive; but the sets are so positioned that the impulses from one set are added to the impulses from the other set. In this manner a protracted impulse is obtained which 'is .capable of actuating indicating mechanism without danger of a flaw being missed.

While I have described an arrangement of three coils above, the same principle may apply to any odd number of coils, as, for example, five coils.- as shown in Fig. 7, which would ordinarily do the work which heretofore required at least four pairs of opposed coils. A material reduction in the number of coils and in the space required for such a unit is thereforeobtained. Thus, coils ll and ll is one pair, ll and 42 a second pair, 42

and 48 a third pair, and 43 and II a fourth pair.

In Fig. 6 form I do not limit myself to two sets of coils where each set comprises but three coils, since each set may consist of any odd number of coils,'three or more.

In Fig. ,8, where the coils are shown oil'set so that the inner end of the core 50 would coact with a portion of the railhead nearer the center thereof than the outer end, it was found desirable to cutv oi! the inner arm, to increase the reluctance of the magnetic circuit which includes the core and 'the railhead and'thereby eliminate indications dueto surface irregularities and to surface burns. The core, therefore, appears as shown in Figs. 8 and 9 with only the outer end thereof provided with arm 5| extending downwardly substantially to the lowermost edge of the coil.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention canbe carried out by other means. Also, while it is designed to use the .various features and, elements iii the combination and relations described. some of these may be altered and others omitted without interfering with the more general resultsoutlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a device for detecting flaws in rails, a detector unit, said unit comprising an induction coil having a core extending therethrough, only one end of said core having an arm extending v downwardly adjacent the rail surface.

2. In a device for detecting flaws in rails, a

detectorunit, said unit comprising an induction cell having a core extending therethrough, one end of said coil and said core being positioned nearer the center of the rail than the other end, only the latter end of said core being provided with an arm extending downwardly adjacent the rail surface.

3. In a device for detecting fiaws in electrical conductors, said dev'ice'having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising three coils conductively connected and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction of current flow through the conductor.

4. In a device for detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising three coils conductively' connected in balanced relation and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction of current flow through the conductor.

5. In a device for detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit; said unit comprising an odd number oi coils more than one. conductively connected and in inductive relation to said conductor, each of said coils comprising a plurality oisubstantiaily parallel turns, each coil being positioned with its axis substantially at right angles to the direction 01' current fiow through the conductor.

6. In a device for detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising an odd number of coils more than one, conductively connected in balanced relation and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each cell being positioned with its axis substantially at right angles to the direction of current fiow through the conductor.

7. In a device ior'detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising three coilsconductively connected and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction 01' current flow through the conductor, one of said coils being balanced against the other two coils.

8. In a device for detecting flaws in electrical conductors, said device having means for passing current through the conductor, to establish an electromagnetic field, a detector unit, said unit conductors, said device having means for passing current through the conductor to establish an electromagneticfield, adetector unit, said unit comprising an odd number of coilsconductively connected and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction 01' current flow through the conductor, certain of said coils each coacting with a plurality of the other coils. I

10. In a device for detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising a plurality of sets oi coils, each set comprising three coils conductively connected and in inductive relation to said conductor, each of said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles 'to the direction of current fiow through the conductor.

11. In a device for detecting flaws in electrical.

conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising a plurality of sets of coils, each set comprising three coils conductively connected a balanced relation and in inductive relation to said conductor, each oi. said coils comprising a pin rality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction 0! current flow through the conductor.

12. In a device'for detecting flaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising a plurality of sets oi coils, each set comprising an odd number of coils conductively connected and in inductive relation to said conductor, each oi said coils comprising a plurality of substantially parallel turns, each coil being positioned with its axis substantially at right angles to the direction of current fiow through the conductor.

13. In a device for detecting fiaws in electrical conductors, said device having means for passing current through the conductor to establish an electromagnetic field, a detector unit, said unit comprising a plurality of sets of cells, each set comprising an odd number of coils conductively connected in. balanced relation and inductive device having means for passing current through the rail to establish an electromagnetic field, a detector unit, said unit comprising three coils conductively connected and in inductive relation to the rail, each oi said coils comprising a pinrality oi substantially parallel turns. each coil being positioned with its axis substantially at right angles to the direction oi current fiow through the conductor, one of said coils-being displaced with respect to the remaining coils laterally oi the rail.

15:11: adevice for detecting flaws in rails, said device having means for passing current through the rail to establish an electromagnetic field, a detector unit, said unit comprising an odd number of coils conductively connected and in inductiverelationtotheraiLeachoi'saidcoilscomprising a plurality oi substantially parallel turns. each coil being positioned with its axis substantially atright angles to the direction 0! current ilow through the conductor, certain of said.coils being displaced with respect to the remaining coils laterally oi the rail.

16. The method oi reducing ialseindications in a rail iissure detector system which consists in passing current through the rail to establish an electromagnetic field surrounding the rail, exploring said field by an' induction coil positioned so as to establish'a magnetic circuit which includes the core of said coil and the railhead. and increasing the reluctance of said circuit above that of a circuit wherein the induction coil has a U-shaped core with arms extending toward the rail substantially to the lowermost edge of the 50 coil.

1'1 In a rail fissure detector mechanism having means for passing current through the rail to establish an electromagnetic iield surrounding the same. an induction coil having a core for exploring said field and positioned so as to establish a magnetic circuit which includes said core and the railhead. said core being so formed as to increase the reluctance of said circuit above that 01a circuit wherein the induction coil has a U-shaped core with arms extending toward the rail substantially to the lowermost edge oi the coll.

18. In a rail fissure detector system, the method which consists in passing current through the rail to establish an electromagnetic ileld surrounding the rail, exploring said held by an induction coil positioned so as to establish a magnetic circuit which includes the coil 0! said core and the railhead. and reducing false indications in said system by increasing the reluctance oi said circuit.

CHARLES B. ROEDE. 

